This invention relates generally to exposure means for originals, positioned along an endless conveyor path. The conveyor means typically passes originals through the conveyor for exposure thereof onto a photoconductor, for example. Drive means are provided to enable repeated passes of the original in one direction. Means are also provided for introducing the original into the conveyor path and for selectively discharging the original from the conveyor path. It is known to include measuring means to determine whether the length of the original that has been introduced is larger or smaller than a predetermined value and to deliver a control signal when the length is smaller.
For example, such an exposure device is disclosed in United Kingdom Pat. No. 1,262,329. That patent describes a device having a second, shorter endless conveyor path which in its exposure station coincides with the longer endless conveyor path. An original is introduced into the shorter path and circulated therein for successive exposures when the measuring means detects an original of a length shorter than the second path.
With this device, it is possible to make a number of exposures without interruption for only those originals having a length corresponding to the length of the endless conveyor path. If the second path is long, the interruptions will be relatively long, resulting in a relatively short exposure time. On the other hand, if the second path is short, only the shortest originals can use the path, while all the longer originals must make use of the much longer endless path corresponding to the length of the longest original, resulting in long interruptions between the successive exposures. This is particularly a problem in the case of relatively short originals.
While is is possible to shorten the length of the conveyor path, the minimum length of an endless conveyor path cannot be made much smaller than about 60 cm, because of the space required to locate the conveyor means, exposure means, and original positioning mechanisms along the path. It is well known that current exposure devices are not well suited for originals shorter than 60 cm, such as, e.g., an original of A3 or A4 size.
Accordingly, it is an object of the present invention to provide an exposure device of the kind referred to above without the limitations of the known exposure device.